Explain why evolution by natural selection can not occur if there is no variation in a characteristic

Why is carbon the key element in forming structural componets of cells

DNA is unwound and transcribed through the action of A - vitamins B - polysaccharides C - cytochromes D - enzymes

What does a nucleotide consist of? a polymer of nitrogenous bases nitrogenous bases and sugar sugar and phosphates a nitrogenous base, a sugar, and a phosphate

Territorial animals like spiders that fight off intruders would be expected to be?

All human cells contain 46 chromosomes; 23 from the dad and 23 from the mom.

What is the value of a transitional fossil? a. Transitional forms show the evolutionary steps between species. b. Transitional forms are analogous fossils. c. Transitional forms discredit the theory of evolution. d.

According to Kepler's second law, which factor is constant as a line between a planet and the sun sweeps out two equal areas at different places as it moves along its orbit? A. The amount of time B. The distance the planet moves C.

The different conservation efforts being applied to protect rainforests.

How would you classify the relationship between the different species of coral?

Which of the following illustrates intraspecific competition? A sea gull swooping down to snatch a fish from the water's surface Male red-winged blackbirds defending limited nesting sites from other males A butterfly feeding on the nectar of a